x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 154 insertions, 0 deletions

diff --git a/sound/soc/meson/aiu-codec-ctrl.c b/sound/soc/meson/aiu-codec-ctrl.c
new file mode 100644
index 000000000..60bb4cdfe
--- /dev/null
+++ b/sound/soc/meson/aiu-codec-ctrl.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (c) 2020 BayLibre, SAS.
+// Author: Jerome Brunet <jbrunet@baylibre.com>
+
+#include <linux/bitfield.h>
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <sound/soc-dai.h>
+
+#include <dt-bindings/sound/meson-aiu.h>
+#include "aiu.h"
+#include "meson-codec-glue.h"
+
+#define CTRL_CLK_SEL		GENMASK(1, 0)
+#define CTRL_DATA_SEL_SHIFT	4
+#define CTRL_DATA_SEL		(0x3 << CTRL_DATA_SEL_SHIFT)
+
+static const char * const aiu_codec_ctrl_mux_texts[] = {
+	"DISABLED", "PCM", "I2S",
+};
+
+static int aiu_codec_ctrl_mux_put_enum(struct snd_kcontrol *kcontrol,
+				       struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *component = snd_soc_dapm_kcontrol_to_component(kcontrol);
+	struct snd_soc_dapm_context *dapm = snd_soc_dapm_kcontrol_to_dapm(kcontrol);
+	struct soc_enum *e = (struct soc_enum *)kcontrol->private_value;
+	unsigned int mux, changed;
+
+	if (ucontrol->value.enumerated.item[0] >= e->items)
+		return -EINVAL;
+
+	mux = snd_soc_enum_item_to_val(e, ucontrol->value.enumerated.item[0]);
+	changed = snd_soc_component_test_bits(component, e->reg,
+					      CTRL_DATA_SEL,
+					      FIELD_PREP(CTRL_DATA_SEL, mux));
+
+	if (!changed)
+		return 0;
+
+	/* Force disconnect of the mux while updating */
+	snd_soc_dapm_mux_update_power(dapm, kcontrol, 0, NULL, NULL);
+
+	/* Reset the source first */
+	snd_soc_component_update_bits(component, e->reg,
+				      CTRL_CLK_SEL |
+				      CTRL_DATA_SEL,
+				      FIELD_PREP(CTRL_CLK_SEL, 0) |
+				      FIELD_PREP(CTRL_DATA_SEL, 0));
+
+	/* Set the appropriate source */
+	snd_soc_component_update_bits(component, e->reg,
+				      CTRL_CLK_SEL |
+				      CTRL_DATA_SEL,
+				      FIELD_PREP(CTRL_CLK_SEL, mux) |
+				      FIELD_PREP(CTRL_DATA_SEL, mux));
+
+	snd_soc_dapm_mux_update_power(dapm, kcontrol, mux, e, NULL);
+
+	return 1;
+}
+
+static SOC_ENUM_SINGLE_DECL(aiu_hdmi_ctrl_mux_enum, AIU_HDMI_CLK_DATA_CTRL,
+			    CTRL_DATA_SEL_SHIFT,
+			    aiu_codec_ctrl_mux_texts);
+
+static const struct snd_kcontrol_new aiu_hdmi_ctrl_mux =
+	SOC_DAPM_ENUM_EXT("HDMI Source", aiu_hdmi_ctrl_mux_enum,
+			  snd_soc_dapm_get_enum_double,
+			  aiu_codec_ctrl_mux_put_enum);
+
+static const struct snd_soc_dapm_widget aiu_hdmi_ctrl_widgets[] = {
+	SND_SOC_DAPM_MUX("HDMI CTRL SRC", SND_SOC_NOPM, 0, 0,
+			 &aiu_hdmi_ctrl_mux),
+};
+
+static const struct snd_soc_dai_ops aiu_codec_ctrl_input_ops = {
+	.probe		= meson_codec_glue_input_dai_probe,
+	.remove		= meson_codec_glue_input_dai_remove,
+	.hw_params	= meson_codec_glue_input_hw_params,
+	.set_fmt	= meson_codec_glue_input_set_fmt,
+};
+
+static const struct snd_soc_dai_ops aiu_codec_ctrl_output_ops = {
+	.startup	= meson_codec_glue_output_startup,
+};
+
+#define AIU_CODEC_CTRL_FORMATS					\
+	(SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S20_3LE |	\
+	 SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_LE |	\
+	 SNDRV_PCM_FMTBIT_S32_LE)
+
+#define AIU_CODEC_CTRL_STREAM(xname, xsuffix)			\
+{								\
+	.stream_name	= xname " " xsuffix,			\
+	.channels_min	= 1,					\
+	.channels_max	= 8,					\
+	.rate_min       = 5512,					\
+	.rate_max	= 192000,				\
+	.formats	= AIU_CODEC_CTRL_FORMATS,		\
+}
+
+#define AIU_CODEC_CTRL_INPUT(xname) {				\
+	.name = "CODEC CTRL " xname,				\
+	.playback = AIU_CODEC_CTRL_STREAM(xname, "Playback"),	\
+	.ops = &aiu_codec_ctrl_input_ops,			\
+}
+
+#define AIU_CODEC_CTRL_OUTPUT(xname) {				\
+	.name = "CODEC CTRL " xname,				\
+	.capture = AIU_CODEC_CTRL_STREAM(xname, "Capture"),	\
+	.ops = &aiu_codec_ctrl_output_ops,			\
+}
+
+static struct snd_soc_dai_driver aiu_hdmi_ctrl_dai_drv[] = {
+	[CTRL_I2S] = AIU_CODEC_CTRL_INPUT("HDMI I2S IN"),
+	[CTRL_PCM] = AIU_CODEC_CTRL_INPUT("HDMI PCM IN"),
+	[CTRL_OUT] = AIU_CODEC_CTRL_OUTPUT("HDMI OUT"),
+};
+
+static const struct snd_soc_dapm_route aiu_hdmi_ctrl_routes[] = {
+	{ "HDMI CTRL SRC", "I2S", "HDMI I2S IN Playback" },
+	{ "HDMI CTRL SRC", "PCM", "HDMI PCM IN Playback" },
+	{ "HDMI OUT Capture", NULL, "HDMI CTRL SRC" },
+};
+
+static int aiu_hdmi_of_xlate_dai_name(struct snd_soc_component *component,
+				      const struct of_phandle_args *args,
+				      const char **dai_name)
+{
+	return aiu_of_xlate_dai_name(component, args, dai_name, AIU_HDMI);
+}
+
+static const struct snd_soc_component_driver aiu_hdmi_ctrl_component = {
+	.name			= "AIU HDMI Codec Control",
+	.dapm_widgets		= aiu_hdmi_ctrl_widgets,
+	.num_dapm_widgets	= ARRAY_SIZE(aiu_hdmi_ctrl_widgets),
+	.dapm_routes		= aiu_hdmi_ctrl_routes,
+	.num_dapm_routes	= ARRAY_SIZE(aiu_hdmi_ctrl_routes),
+	.of_xlate_dai_name	= aiu_hdmi_of_xlate_dai_name,
+	.endianness		= 1,
+#ifdef CONFIG_DEBUG_FS
+	.debugfs_prefix		= "hdmi",
+#endif
+};
+
+int aiu_hdmi_ctrl_register_component(struct device *dev)
+{
+	return snd_soc_register_component(dev, &aiu_hdmi_ctrl_component,
+					  aiu_hdmi_ctrl_dai_drv,
+					  ARRAY_SIZE(aiu_hdmi_ctrl_dai_drv));
+}
+